![]() ![]() This process is experimental and the keywords may be updated as the learning algorithm improves. These keywords were added by machine and not by the authors. After World War II, all activities were consolidated in Orlando under the direction of Owen Owsley and the auspices of the Office of Naval Research (ONR). Measured acoustic calibration results for a small subset of receive elements and the projector are presented. In this paper we calculate theoretically the sequence of bubble shapes from a given nozzle and show that there is for each nozzle a. Also the issues of dicing and backfilling of the inter-element interstices will be addressed. Air bubbles released from an underwater nozzle emit an acoustical pulse which is of interest both for the study of bubble detachment and for elucidating the mechanism of sound generation by a newly formed bubble. Various material trade-offs associated with the selection of the: 1) active layer, 2) backing layer, 3) mechanical, and electrical connections are discussed. In both cases the active material was piezoceramic. The Bermuda Research Detachment, Tudor Hill Laboratory after layout of Naval Underwater. Both projector and receive elements were designed to achieve a minimum 3dB beam width of 30 degrees at 1.5 MHz. That year, the Underwater Sound Laboratory from New London. The ultrasonic spherical cap projector element had a 29 mm radius of curvature and an active angular aperture of 40 degrees. ![]() 89) mm, with a center spacing of 1.07 mm. The present article describes further research on the technique, including a description of a successful application to measurements made under nonatmospheric hydrostatic pressure. The method is based on leastsquares fitting to a multiplelayer model. The individual receive element dimensions were (.91 ×. 81, 12461258 (1987) described a new technique for evaluating underwater panel measurements. Containing over a quarter million diced elements, and a centrally located, constant beam width, spherical cap projector, the complete array was to consist of 25 modules, of which the central module is described. Equations are developed, suitable for programmable calculators, which analyze the ac and dc conditions in the circuit.The design, construction, and measured results for a prototype module of probably the world’s largest dense packed, two dimensional, ultrasonic (1.5 MHz), receive array is described. It operates on a single power supply and has a 100-kHz bandwidth. ![]() Its self-noise is typically -118 dBV for a 1-G ohms input impedance. The preamplifier circuit described has been optimized at the Underwater Sound Reference Detachment of NRL into a rugged integrated (hybrid) circuit suitable for low-noise hydrophone applications. The further development of hybrid techniques has allowed these amplifiers to shrink greatly in size and cost. These waves may be man-made or naturally generated. These compressions and rarefactions are detected by a receiver, such as the human ear or a hydrophone, as changes in pressure. The introduction of the junction field-effect transistor (JFET) resulted in hydrophone preamplifier designs having low-noise, high input impedance, broad bandwidth, and wide dynamic range. A sound wave propagating underwater consists of alternating compressions and rarefactions of the water. Since the early 1960's, remarkable growth has occurred in the quality of electronic amplifier design for underwater applications. It also describes how the circuit has been miniaturized to hybrid form and packaged in a TO-99 can. This report presents a dc and low-frequency ac analysis of a low-noise preamplifier design. ![]()
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